AdrianM

n have a fox stepped reamer. I reamed an APC 12.25x3.75 last weekend and put it on a plane. It shook so bad the low speed needle fell out!

I hadn't had problem like this with APC props before so i put it on my balancer and it was WAY OUT. On closer inspection i saw that the hole in the prop wasn't centered.

Got prop #2 the hole looked off center when new, reamed it carefully, put it on the balancer...it was crap too.

Called APC, asked what to do. The guy there said to use a tapered reamer and ream from the back to the front. Third prop, the hold appeared to be off center too. Carefully reamed it with the tapered reamer...crap again.

Got on RCU searched for !QUOT!reaming!QUOT! saw a tapered reamer was the way to go but do it front to back because the rear of an APC prop is the most accurate part of the mold. Got my last prop reamed from to back. Best result so far but still not perfect.

Am I wrong to think that the round center section of the prop should be perfectly concentric with the center hole? I put on the balancer, give it a good spin and I see the center of the prop wobble up and down.

When I balance the prop the blades balance but the its like one half of the hub is heavier and alway settle on the bottom. Can I sand the heavy part of the prob hub? Will this weaken it? Did I just nuke $18 in props?

sandhillflyer

My Feedback: (1)

Did APC give any answer as to why the hole is not centered from the factory? I just received 4 new 12 inch APC props and the hole in 2 is not centered. I reamed one from the back with my Fox reamer and the collar on the back of the prop seemed to recenter the hole.

Mark

Geistware

My Feedback: (16)

I would suggest that you try to balance the propeller before you ream/drill it. Then check it after. I do this to see if I screwed up the process.

Combat Addict

You got reamed.

I use a step reamer, it works well for Master Airscrew nylon reinforced, and wood props. Not sure about tappered though. I would be carefull with those.

AdrianM

When you balance a prop can you grind on the hub to make the hub balanced?

Ed Smith

The centre hole is a drilled hole and not necessarily true. The true part is the molded larger hole in the back of the hub. A bushinng is required that is a fit in that hole and on the engine crankshaft. With the pylon props we purchase included is a "Twig" with four plastic bushings of various sizes.

A Propellor has to be balanced in such a way that it will stop in any position on the balancer. If the prop always comes to rest in a horizontal position with the same side of the hub down then that side of the hub is heavy or the hole being used to balance is not in the centre. Do not use the drilled hole for balancing, use the molded holes in the back and front of the hub. Balance the blades first. It is then sometimes necessary to grind some material from the side of the hub to balance the prop.

Ed S

twostroke

My Feedback: (6)

I think I would start buying a different kind of prop if the hole is off center reaming it will just make a bigger hole off center.

AdrianM

For Props up to ~18" you cant beat APC. I've tried Graupner, Top Flite, Rev-Up,...etc. and not of them have the pull of an APC.

Ed-I have heard about these bushings but I have never seen them. The hole in the back of the sport props i use probably wouldnt take them.

Geistware

My Feedback: (16)

Spinners usually come with thse plastic bushings. You can also get some from Ace Hardware.

Combat Addict

Do you have to use APC? I would try a Master Airscrew if it is just for sport flying

Flyboy Dave

My Feedback: (21)

Yes, you can remove some material from the hub to
balance the prop, if one side of the hub is heavy.
I just grind a bit at a time with the belt sander. I have
only had to do this on very large props.

If the hole is not centered in the prop hub....don't buy
the prop. It would be very hard to drill it back straight,
and with the hand reamer, it will end up the way it started out....off center.

I always use the drill press to enlarge the hole in the
prop. I just hold the prop lightly against the drill press
table, and bring the drill bit down against it very lightly
....allowing the bit to center in the existing hole....then
hold down tight on the prop, and drill it through.

I use wood, and Master Airscrew props, mainly because
I think they look better, work just fine, and are easier
to balance. Some guys prefer the APC props....but I've
found them too far out of balance to work with, hard
to get balanced, because they are hard too sand, too
brittle....and break easily, and are too darned sharp and
are kind of dangerous IMO. I have not seen any increase
in performance with the APC's over the Zingers, and the
MAS .

Dave.

SwampFlier-RCU

Adrina I just reamed a couple of APC props (first time) with a reamer (conical ) not step and the way I did it is to start at the back until you ghet halfway of the hub (the reamed part not the whole hub) and then turn around and ream from the fron, trying to get the reamer to eat away at the middle of the ramed area, since they are hand reamers you tend to apply pressure to one side and if you misalign it, when you star onthe oposite sidd ti heleps starighten it.
I think Flyboy's suggestion is good and would use it but alas.. I don't have a drill press...
BEa creful when you are reaming the prop do it slow and checking the progress of your work

NOVAflier

My Feedback: (21)

I have a metric and a standard step reamer, and have never had a problem. Throw the tapered one away and get a step reamer... Just my opinion..